Clear Creek / North Clear Creek Overview � Highlight Past Improvements � Discuss Feasibility Study & Record of Decision North Clear Creek � Metals of Concern Zinc, Copper, Manganese Cadmium, Aluminum, Iron
The Upper Clear Creek Watershed and Superfund Study Area
Clear Creek / Central City Superfund Site
Completed Remediation Efforts on Main Stem of Clear Creek � 1994 - Present Mine Waste Pile Cleanups � 1998 - Argo Water Treatment Plant
Argo Tunnel
Pre Q (cfs) Downsteam Idaho Springs, Dis-Zn Post Q (cfs) Pre D-Zn Post D-Zn 900 750 Dis-Zinc Conc., ug/L 600 Streamflow, cfs 600 450 300 300 150 0 0 Autumn Winter Spring Summer Quarter
Pre D-Zn Downsteam Idaho Springs, Dis-Zn Post D-Zn 750 Dis-Zinc Conc., ug/L 600 450 300 150 0 0 Autumn Winter Spring Summer Quarter
Seasonal Hardness High Flow Low Flow May 1 September 1 Segment Through through August 31 April 30 North Clear Creek 80 184 Segment 13b Clear Creek 53 103 Segment 11
Clear Creek Below Idaho Springs and at Golden Dissolved Zinc Pre Q (cfs) Kermits, Dissoved Zinc Post Q (cfs) Golden Dissolved Zinc, Pre- vs. Post-4/98 Pre D-Zn 900 600 900 600 Post D-Zn D is -Z in c C o n c ., u g /L D is-Z in c C o n c., u g /L S tream flo w , cfs S tre a m flo w , c fs 600 400 600 400 300 200 300 200 0 0 0 0 Autumn Winter Spring Summer Autumn Winter Spring Summer Quarter Quarter
Summary of Remedial Action Objectives North Clear Creek to Improve North Clear Creek � � North Clear Creek is significantly impaired. Improvement of surface water quality to a point that is protective of aquatic life (i.e., survival of a brown trout population) is a goal of the OU4 remedy. North Clear Creek to Improve Clear Creek. � Do not degrade drinking water supplies obtained from Clear � Creek. Reduce the toxicity to aquatic insects by reducing metal in � sediments. Control or reduce runoff from tailings/waste rock piles to � reduce sediment loading of streams and ground water. � Sediment loading from the piles continues to degrade water quality and habitat in receiving streams, and may continue to limit habitat for aquatic life.
High Flow Low Flow
Priority Waste Piles . Pile Remedial Action Old Jordan Remove (to Druid) Niagra Remove Mattie May Cap with Rock Baltimore Cap with Rock Centennial Remove Pittsburgh Cap with Rock Upper Nevada Gulch Soil Cap and Revegetate Piles (northern aspect) Upper Nevada Gulch Cap with Rock (southern aspect) Piles Gregory Gulch No. 3 Remove Argo Cap with Rock Druid Soil Cap and Revegetate Iroquois Cap with Rock Anchor Soil Cap and Revegetate Hazeltine Soil Cap and Revegetate
North Clear Creek Removal Needed Low Flow Concentration/Mass Zinc Copper Cadmium Manganese Iron Flux (dissolved) (dissolved) (dissolved) (dissolved) (total recoverable) Current Low-Flow Conditions Concentration 1,657 15.5 6.0 3,579 7,856 ( μ g/L) Low-Flow Goals Concentration 675 15.1 3.5 2,021 5,400 ( μ g/L) Load Reduction Required to Goals Under Low-Flow Conditions Percent 59% 2% 41% 44% 31% Reduction
Alternatives Considered � Alternative 1A & B No Action / Institutional Controls � Alternative 2A & B Tier 1 Sediment Reduction (Tributaries and North Clear Creek) � Alternative 3A, B & C Water Treatment at Argo, at New Plant in NCC, varying Tiers of Sediment Reduction � Alternative 4A & B Passive (Wetland Substrate), Combined Active and Passive Water Treatment with Tier 2 Sediment
Preferred Alternative (4B) � Treatment of Gregory Incline and Gregory Gulch ground water at Bates Hunter � Treatment of National Tunnel with a wetland � Sediment Controls – Detention ponds & mine waste capping on Russell & Gregory Gulch � North Clear Creek improvements � Cost 11.8 Million, $900,000 / year operations
High Flow Low Flow
Anticipated Load Reduction (NCC) Alternative 4B Percent Reduction in Loading for the Given Flow Regime Source Area Low-Flow High-Flow Gregory Incline 99% 85% National Tunnel 85% 85% Gregory Gulch 25% 45% Russell Gulch 20% 40% Chase Gulch 10% 5% Non-Point Sources 40% 40%
Capped Surface Volume Length of Channel Waste Pile Remedial Action Area Removed Stabilization (acres) (cy) (ft) Old Jordan Remove (to Druid) 2,900 200 Mattie May Rock Cap Baltimore Rock Cap 10.0 2,700 Argo Rock Cap Pittsburgh Rock Cap Druid Soil Cap 19.0 Upper Nevada Gulch Rock Cap 16.5 4,800 (South Aspect) Upper Nevada Gulch Soil Cap 16.5 (North Aspect) Gregory Gulch #3 Remove 3,700 300 Centennial Remove 1,500 100 Niagra Remove 5,600 200 Iroquois Rock Cap 3.0 300 Hazeltine Soil Cap 0.9 300 Anchor Soil Cap 1.9 300 Total 67.8 13,700 9,200
Provide Comments on the Proposed Plan
Next Steps � Public Comment 8/23 � Agencies consider comments and prepare a Record of Decision by 9/30/2004
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